1. Field of the Invention
The present invention relates to a method of managing an allocated address in a low power wireless personal area network.
2. Description of the Related Art
In general, a Personal Area Network (PAN) differs from a Local Area Network (LAN) or a Wide Area Network (WAN), and in the PAN, each person has an inherent network. A PAN can be used in diverse fields such as a wireless sensor network, a home network, and the like. In order to wirelessly implement the PAN, diverse standards have been proposed, and one of such standards is the Low power Wireless Personal Area Network (LoWPAN), which is a wireless sensor network implemented using the Institute of Electrical and Electronics Engineers (IEEE) 802.15.4 standard.
Also, LoWPAN, to which an Internet Protocol-Ubiquitous Sensor Network (IP-USN) based Internet Protocol (IP) version 6 is applied, is referred to as 6LoWPAN. 6LoWPAN includes a PAN coordinator which provides an outside interface and serves as a whole manager managing the routing and synchronization of nodes included in the 6LoWPAN, a coordinator or a Full Function Device (FFD) that supports the routing function, and a Reduced-Function Device (RFD) that does not support the routing function. The PAN coordinator manages addresses to be allocated to all nodes included in the 6LoWPAN. Since the address has a hierarchical network structure and an address system, such as ZigBee, and is mainly composed of 16 bits for its energy efficiency, the addresses are limited in number.
The coordinator (or FFD) allocates an inherent address to an RFD or its child node which has entered into its communication region, and the address allocated to the child node is one of the addresses managed by the PAN coordinator. In this case, the FFD or RFD is allocated with an address for communicating with a parent node through the parent node that has a one-hop connection with the FFD or RFD. The parent node may be a coordinator (or FFD) that supports the routing function.
LoWPAN provides diverse services and application programs as it evolves into a network that supports not only a simple data sensing process in the existing sensor network but also an IP environment in the IP-USN. An example of the IP-USN application and implementation may be a coupon service, which will now be described in detail.
First, in a crowded shopping area, each store is provided with nodes for coupon services. In the case where a customer has a portable terminal, each store can receive coupon services from an external server (e.g. a chain store), and the customer can inquire about the details of an interested coupon service. The hierarchical structure for such coupon services is similar to the hierarchical LoWPAN environment of the IP-USN. That is, the chain store corresponds to the PAN coordinator, the node of each store corresponds to the coordinator (or FFD), and the customer's portable terminal corresponds to the RFD. In this environment, the customer's portable terminal, i.e. the RFD, is required to receive the coupon services during the movement of the portable terminal.
However, the address management policy (or algorithm) in the current LoWPAN takes into consideration only fixed nodes, and due to the limited resources and the energy efficiency of LoWPAN, it is difficult to apply the address management policy (or algorithm) to the mobile IP environment having a large amount of data and a wide communication bandwidth. Accordingly, there is a need for a scheme for efficiently managing addresses that takes into consideration mobile nodes in LoWPAN.